Differential signal transmission
View Patent ↗Transport of differential signals is provided. In one aspect, a telecommunications system includes a first unit and a second unit. The first unit can calculate a differential signal from an original signal. The differential signal can represent a change in signal levels between constant time intervals in the original signal. The second unit can estimate the original signal from the differential signal received from the first unit over a communication medium.
1. A telecommunications system, comprising:
a first unit for calculating a differential signal from an original signal, the differential signal representing a change in signal levels between constant time intervals in the original signal; and
a second unit for estimating the original signal from the differential signal received from the first unit over a communication medium,
wherein the first unit includes at least two units and the differential signal includes a first differential signal calculated from a first original signal and a second differential signal calculated from a second original signal,
wherein the second unit is adapted for estimating the original signal by estimating a summed original signal from a sum of the first differential signal and the second differential signal, wherein the second unit includes:
a first summer for summing the first differential signal and the second differential signal;
a second summer for producing a cumulative sum signal using the summed differential signals; and
a third summer for producing an estimated summed original signal using a mean estimate and the cumulative sum signal.
2. The telecommunications system of claim 1 , wherein the second unit is adapted for receiving the differential signal without receiving the original signal.
3. The telecommunications system of claim 1 , where the first unit is a head unit of a distributed antenna system and the second unit includes a plurality of remote units for providing wireless coverage in an environment.
4. The telecommunications system of claim 1 , wherein the first unit is adapted for digitizing the original signal to produce a digitized signal and for calculating the differential signal from the digitized signal,
wherein the second unit is adapted for estimating the digitized signal to produce an estimated digitized signal and for converting the estimated digitized signal to an estimated original signal.
5. The telecommunications system of claim 4 , wherein the first unit is adapted for calculating the differential signal from the digitized signal by subtracting a signal level of a first digital sample from the signal level of a second digital sample.
6. The telecommunications system of claim 1 , wherein the first unit is configured for using adaptive quantization on the differential signal for reducing required bandwidth to transmit the differential signal.
7. The telecommunications system of claim 1 , wherein the original signal is a zero-mean signal.
8. A telecommunications system, comprising:
a remote unit of a plurality of remote units of a distributed antenna system, the remote unit being adapted for calculating a differential signal from an original signal that is a zero-mean signal, the differential signal representing a change in signal levels between constant time intervals in the original signal; and
a head unit of the distributed antenna system, the head unit being adapted for estimating the original signal from the differential signal received from the remote unit over a communication medium without receiving the original signal,
wherein the differential signal includes a first differential signal calculated from a first original signal and a second differential signal calculated from a second original signal,
wherein the head unit is adapted for estimating the original signal by estimating a summed original signal from a sum of the first differential signal and the second differential signal, the head unit including:
a first summer for summing the first differential signal and the second differential signal;
a second summer for producing a cumulative sum signal using the summed differential signals;
a highpass filter for filtering the cumulative sum signal; and
a mixer for frequency shifting the cumulative sum signal to produce an estimated summed original signal.
9. The telecommunications system of claim 8 , where the plurality of remote units is adapted for providing wireless coverage in an environment, wherein the head unit is for communicating with a base transceiver station.
10. The telecommunications system of claim 8 , wherein the remote unit is adapted for digitizing the original signal to produce a digitized signal and for calculating the differential signal from the digitized signal,
wherein the head unit is adapted for estimating the digitized signal to produce an estimated digitized signal and for converting the estimated digitized signal to an estimated original signal.
11. The telecommunications system of claim 10 , wherein the remote unit is adapted for calculating the differential signal from the digitized signal by subtracting a signal level of a first digital sample from the signal level of a second digital sample.
12. The telecommunications system of claim 8 , wherein the remote unit is configured for using adaptive quantization on the differential signal for reducing required bandwidth to transmit the differential signal.
13. A distributed antenna system, comprising:
a first remote unit adapted for calculating a first differential signal from a first original signal;
a second remote unit adapted for calculating a second differential signal from a second original signal; and
a head unit for estimating a sum of the first original signal and the second original signal from the first differential signal and the second differential signal received over at least one communication medium from the first remote unit and the second remote unit, the head unit including:
a first summer for summing the first differential signal and the second differential signal;
a second summer for producing a cumulative sum signal using the summed differential signals;
a highpass filter for filtering the cumulative sum signal; and
a mixer for frequency shifting the cumulative sum signal to produce an estimated summed original signal.
14. The distributed antenna system of claim 13 , wherein each of the first original signal and the second original signal is a zero-mean signal,
wherein each of the first differential signal and the second differential signal represent a change in signal levels between constant time intervals in a corresponding original signal.